(1) Field of the Invention
This invention relates to fluid displacement machines, also known as volumetric machines, in which a rotor is mounted for rotation within a substantially cylindrical hollow chamber, the rotor being mounted for rotation about about an eccentric axis so that the rotor is contiguous with the chamber wall along a generatrix. The chamber wall constitutes the stator of the machine, and one or more working spaces are then formed between the internal surfaces of the hollow chamber and the outer surface of the rotor. More specifically, the invention is concerned with machines in which the rotor is equipped with a number of radial, or substantially radial, vanes which contact the wall of the chamber so as to separate a number of working spaces which, during rotation of the rotor, move around the chamber while periodically varying in volume between inlet and outlet ports for a driving or driven fluid. Examples of such machines are motors, compressors or vacuum pumps which operate with fluid gases, pumps or hydrodynamic motors which operate with liquids and internal combustion engines. A substantial variety of such machines are commerically available.
(2) Description of the Prior Art
In machines of the above type which are intended to work at relatively low speeds of rotation the vanes are urged outwardly against the cylindrical surface of the chamber by means of springs contained in the rotor itself. When the speed of rotation is higher the centrifugal force acting on the vanes, which of course rotate with the rotor, is sufficient to maintain the circumferential edges of the vanes in contact with the wall of the chamber. This is satisfactory when speeds are moderate and lubrication conditions are optimum. However it is not satisfactory for yet faster machines because the centrifugal force is still greater and drives the vanes against the wall of the chamber so forcefully that friction causes unacceptable wear to the equipment and unacceptable losses of energy.